1. Field of the Invention
The present invention pertains to polyurethane elastomer compositions. More particularly, the present invention concerns pigmented polyurethane elastomer compositions. Even more particularly, the present invention concerns pigmented polyurethane elastomer compositions of reduced thixotropy.
2. Prior Art
The use of pigmented urethane elastomers in athletic surfacing, e.g. gymnasia, tennis courts and the like is known. In applying these elastomers it is essential that no ripples in the surface occur at the knit line thereof. If such ripples occur, then, the surface is substantially worthless. More specifically because of the large areas to be covered, the liquid uncured elastomer must be poured in a series of strips to cover the entire surface. When these strips flow together, a "knit line" sometimes results. This knit line may indicate an irregular surface in the immediate vicinity. This irregular surface is undesirable both from an aesthetic point of view and from a practical standpoint if the surface is to be used as a tennis court. Thus it is highly desirable that this type of poured athletic surface be completely free from any irregularities.
It has been observed that the creation or absence of ripples is a direct function of the flow behavior of the pigmented urethane elastomer composition. Thus, it is highly desirable that the uncured elastomer not only have a low viscosity but that the viscosity be as close to Newtonian as possible. Hence, the ideal herein is a low viscosity Newtonian fluid. Mere reduction in viscosity, alone, however, is insufficient to achieve the desired result.
The present invention, as will subsequently be detailed, provides an improved pigmented urethane elastomer of reduced viscosity and nearly Newtonian flow characteristics.
To the best of applicant's knowledge, the most closely related art is found in U.S. Pat. Nos. 3,626,023 and 3,645,979 as well as Canadian Pat. No. 769,107.